A filesystem is simply a way of organizing data in computer-accessible form on the hard disk or other media. Different filesystems have different organizing structures to determine where the data and indexing information will be stored. Some popular filesystems include:

ext2 one of the oldest and most universally supported filesystems on Linux, Unix, and BSD operating systems
ext3 an extended version of ext2 which overcomes some limitations and adds journaling
ext4 fourth extended filesystem - it is a journaling file system for Linux, developed as the successor to ext3.
btrfs
reiserfs an enhanced journaling filesystem written by Hans Reiser and extended by the open source community since his incarceration
jfs
xfs
fat or
vfat the file allocation table-based filesystem used by MS-DOS and Windows 9x
NTFS A more advanced (than fat) filesystem used by Windows NT, 2000, XP and Vista

When doing an installation there is normally a minimum disk configuration of two partitions that needs to be created:

/ (root): directory that contains the Linux distribution.

Swap space: partition that allows a kernel to run more processes than can normally fit into RAM.

If multiple disks are available it is good practice to also have the /usr and /home directories on different partitions. Each partition will contain a filesystem type and can be mounted on the active system in the filesystem global tree. To print the active mounted filesystems, use mount.

Before deciding on your partitioning scheme, you really need to know exactly what sort of applications you will be running.

Mail Server

Web Server

Graphical X-Windows based applications

And more

If your system has multiple disks, use the fastest one to store most of your data.

/ Contains most of the system utilities and doesn't get used much. These can be shipped off to the slowest disk.

/var/log contains a lot of logging information. Best on a fast disk.

/usr is typically on a separate partition anyway and if you have a lot of clients starting lots of X applications, use a fast disk.

Examples of system applications:

For e-mail serving, Sendmail writes to two main locations: mail queue, usually /var/spool/mqueue and /var/spool/mail as well as other locations. Apache uses several different files, two log files per site hosted for logging and access to the actual pages. Apache spends quite a bit of time writing to log files in /var/log (or where configured to do so).

When you set up a new system, swap should be twice your actual RAM. This is not always sensible in real-world scenarios, however it is a traditional guideline and a conservative answer to give in an exam.